Wyniki wyszukiwania - Biblioteka Nauki

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Polydiagnostics performed on high - tech plasmas

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van der Mullen J. J. A. M. , Palomares J. M. , Iordanova E. , Hübner S. , Carbone E. A. D.

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tom Vol. 57, No. 2

147-155

EN

The large effluxes generated by high-tech plasmas force plasmas to non-equilibrium conditions. This implies that plasma features are decoupled from each other and that therefore different methods have to be used quasi-simultaneously to characterize the plasma. Even more insight in plasmas and methods is obtained if polydiagnostics is applied to a series of plasma conditions that gradually differ in equilibrium departure. After discussing methods of passive and active spectroscopy, we apply polydiagnostics on an argon plasma operated in open air. By introducing H2 and reducing the power we approach conditions of cool atmospheric plasmas (CAPs). It is seen that especially the passive methods for the electron temperature determination are very sensitive to the degree of equilibrium departure suggesting that active spectroscopy is preferable. However, one should realize that lasers can easily heat cool plasmas. This is due to the fact that the ionization degree of (semi-) CAPs is small.

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The performance of passive methods of detecting island operation implemented in PV inverters during selected disturbances in distribution power grids

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Parol M. , Połecki M. , Parol M. , Połecki M.

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nr 5

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The performance of passive methods of detecting island operation implemented in PV inverters during selected disturbances in distribution power grids

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Parol M. , Połecki M.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2020

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tom Vol. 68, nr 5

1087--1098

EN

Distributed generation is an issue intensively studied in recent years. It concerns, among others protection systems of distributed generation units connected to electric power grids. The main goal of this paper is to present the issue of functional reliability of selected passive loss of mains (LoM) protection systems, i.e. methods of detecting island operation in distribution power grids, which are implemented in PV inverters installed in sample MV and LV grids, typical for Polish conditions. First, different methods of detecting island operation have been distinguished and shortly characterized. Some problems concerning their action have also been presented. Then commonly used passive methods of island grid operation detection have been described. Next sample distribution grid has been presented and chosen disturbances modelled in the grid to test mentioned passive methods have been defined. For each of the determined type of disturbance the dynamic simulation has been carried out, as well as voltage and frequency plots for two selected RES nodes have been recorded and observed. All considered passive methods of island grid operation detection have been implemented in a Matlab/Simulink environment. Models of RoCoF, U/OVP and U/ OFP algorithms have been presented in diagrams. Then, results of carried out extensive studies have been shown in tables and discussed. The results are a consequence of a realized research project concerning electric grids in rural areas. Summary, final conclusions, and future research possibilities constitute the last part of the paper. The conclusions are mainly concentrated on evaluation of action of passive methods of island operation detection as well as possibility of using the methods in Polish conditions, particularly in rural distribution grids.

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Aktywne tłumienie hałasu

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Ogonowski Z.

Śląskie Wiadomości Elektryczne

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2003

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tom Nr 2 (47)

2--8

PL

W artykule przedstawiono problem zwalczania hałasu jako jednego z czynników szkodliwych dla naturalnego środowiska człowieka - metodami aktywnymi. Autor omawia te metody, przedstawiając je jako alternatywę i uzupełnienie pasywnych sposobów tłumienia. Szczególną uwagę zwraca na aspekty sprzętowe i algorytmiczne aktywnego tłumienia hałasu oraz potrzebę współpracy specjalistów z dziedziny akustyki, automatyki i elektroniki.

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The verification of a piezoelectric vibration-suppression system with a multimode basic RLC shunt circuit and its comparison to a multi-mode current-flowing shunt circuit

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Ścisło Ł.

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tom Vol. 117, iss. 1

art. no. e2020002

EN

One of the modern methods of reducing vibrations of plates and beams is using piezoelectric materials in the form of distributed elements or patches (applied in a passive or an active system). However, for the multimodal response of a structure, there is no possibility to place the actuators in exactly the areas with maximum curvature values for each mode. Additionally, in the case of passive multimodal suppression systems – in which energy is needed to be supplied to the system – there is the necessity to create a complicated electrical circuit. The particular electrical shunts of the circuit are tuned to the specific vibration forms which require damping. The main objective of this article is to show the possibility of creating a multimodal vibration suppression system with typical resonant shunts and proposed second slightly modified.

PL

Jedną z metod redukcji drgań jest wykorzystanie elementów piezoelektrycznych w postaci przyklejonych warstw elementów lub rozłożonych na powierzchni struktury plastrach (w systemie pasywnym lub aktywnym). W przypadku tłumienia wielomodalnego nie jest możliwe znalezienie najlepszego miejsca dla wszystkich form jednocześnie. Dodatkowo w przypadku tłumienia pasywnego, gdzie wymagane jest dostarczenie energii do systemu, dla tłumienia wielomodalnego istnieje konieczność stworzenia skomplikowanego obwodu elektrycznego dostrojonego do częstotliwości rezonansowej konkretnych form drgań własnych. W artykule poruszono temat pasywnego tłumienia wielomodalnego belek. Zaprezentowano typowy sposób stworzenia obwodu eklektycznego oraz porównano z przypadkiem zmodyfikowanego obwodu.